The role of basally synthesized nitric oxide in modulating the renal vasoconstrictor action of angiotensin II.
Interactions between nitric oxide (NO) and angiotensin (ANG) II in renal vascular beds were examined in anesthetized dogs. The renal blood flow (RBF) response to an intrarenal arterial injection of ANG II was significantly augmented by intrarenal infusion of the NO synthase inhibitor N(G)-nitro-L-arginine (LNA, 50 microg/kg/min). The simultaneous intrarenal infusion of L-arginine (1 mg/kg/min) prevented the potentiating action of LNA. Similar potentiation was also seen in phenylephrine-induced renal vasoconstriction. Moreover, during simultaneous intrarenal infusion of sodium nitroprusside (SNP), an NO donor, the potentiating action of LNA on the renal vasoconstrictor action of ANG II disappeared. Under these conditions, the released NO stimulated by ANG II was still inhibited by LNA, if present, but basally released NO was resupplied by SNP, as indicated by the return of the RBF. During an infusion of phenylephrine, which produced an increase in renal vascular tone similar to that observed during the infusion of LNA, the renal vasoconstrictor action of ANG II was not augmented. These data suggest that basally released NO plays an important role in the regulation of renal hemodynamics by modulating the renal vasoconstrictor actions of ANG II and phenylephrine.
Aki
Y
Y
Department of Pharmacology, Kagawa Medical University, Japan.
Tomohiro
A
A
Nishiyama
A
A
Kiyomoto
K
K
Kimura
S
S
Abe
Y
Y
D000804:Angiotensin II / Q000037:antagonists & inhibitors / Q000502:physiology*; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D001120:Arginine / Q000494:pharmacology; D004285:Dogs; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D007668:Kidney / Q000098:blood supply* / Q000187:drug effects / Q000502:physiology; D008297:Male; D009129:Muscle Tonus / Q000187:drug effects / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D019335:Nitroarginine / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D012077:Renal Artery / Q000187:drug effects; D012079:Renal Circulation / Q000187:drug effects; D013777:Tetrazoles / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D000959:Antihypertensive Agents; D004791:Enzyme Inhibitors; D011725:Pyridines; D013777:Tetrazoles; D014662:Vasoconstrictor Agents; C084927:forasartan; D000804:Angiotensin II; D009599:Nitroprusside; D010656:Phenylephrine; D019335:Nitroarginine; D009569:Nitric Oxide; D001120:Arginine; D019001:Nitric Oxide Synthase